Labor leader Mark Latham said yesterday he would oppose the widespread extension of heroin trials beyond an existing scheme in Sydney's Kings Cross, while Prime Minister John Howard committed his Government to doing "everything it can" to stop the spread of the rooms.

Mr Latham said: "My view is that these trials are only appropriate in areas where you have a high user population, so really I'd see Kings Cross as a one-off. I wouldn't support trials anywhere else."

Mr Latham's words are significantly less sympathetic to the concept of heroin trials than Labor has been in the past.

"I'm eager to see what evidence and findings come out of the trial at Kings Cross," he said in Gosford yesterday. "If it's a failure, it should be closed down. If it's a success, it should be up to the state governments to determine what happens with it."

Having been accused by Prime Minister John Howard of being soft on drugs, Mr Latham said his approach was to be "very committed to finding solutions".

He said he was a great admirer of Odyssey House in his electorate which had a "cold turkey, very, very disciplined, ultra-no-tolerance approach".

In 1997, Mr Latham expressed support for heroin trials. He said then: "I would think it's just common sense to have heroin addicts in a controlled environment where there's proper supervision." Meanwhile, in Perth, Mr Howard said the Federal Government's "Tough on Drugs" policy had resulted in a 67 per cent fall in heroin deaths among people aged 15 to 55 since 1999.

Mr Howard announced a funding boost of $6.6 million for community organisations helping in the battle against drug addiction. The Government has spent $1 billion since 1996 on the Tough on Drugs strategy.

Mr Howard said the lives already saved were "worth a billion dollars".

He stressed that the Government had an "uncompromising" approach to drug addiction, centred on its zero-tolerance strategy.

He said the Government would do everything in its power to stop heroin-injecting rooms, which he said were primarily a state responsibility.

Mr Howard ran into some opposition while making his announcement. Craig Scott, who runs an outreach program for drug addicts, which includes a needle exchange program, in Busselton, Western Australia, said heroin rooms were needed as part of the strategy of minimising harm to addicts while they were being treated.

In other pronouncements, Mr Latham also made it clear that under a Labor government gay couples would not have the right to get married but laws that discriminated against them would be changed.

Labor's national conference at the weekend pledged to conduct a national audit of Commonwealth legislation, removing discrimination against same-sex couples from the superannuation, migration, taxation and other laws.

And a swift and angry public response appears to have deterred Mr Latham from selling Kirribilli House, the prime ministerial residence in Sydney. Instead, he is now looking at ways of making it a public space.

"I hadn't thought through the different scenarios, but... having had a chance to think about it over the past couple of days, a sale wouldn't be appropriate," he said.